Christopher K. Pham

Marine litter distribution and density in European seas, from the shelves to deep basins

Anthropogenic litter is present in all marine habitats, from beaches to the most remote points in the oceans. On the seafloor, marine litter, particularly plastic, can accumulate in high densities with deleterious consequences for its inhabitants. Yet, because of the high cost involved with sampling the seafloor, no large-scale assessment of distribution patterns was available to date. Here, we present data on litter distribution and density collected during 588 video and trawl surveys across 32 sites in European waters. We found litter to be present in the deepest areas and at locations as remote from land as the Charlie-Gibbs Fracture Zone across the Mid-Atlantic Ridge. The highest litter density occurs in submarine canyons, whilst the lowest density can be found on continental shelves and on ocean ridges. Plastic was the most prevalent litter item found on the seafloor. Litter from fishing activities (derelict fishing lines and nets) was particularly common on seamounts, banks, mounds and ocean ridges. Our results highlight the extent of the problem and the need for action to prevent increasing accumulation of litter in marine environments.

Deep-water longline fishing has reduced impact on Vulnerable Marine Ecosystems

Bottom trawl fishing threatens deep-sea ecosystems, modifying the seafloor morphology and its physical properties, with dramatic consequences on benthic communities. Therefore, the future of deep-sea fishing relies on alternative techniques that maintain the health of deep-sea ecosystems and tolerate appropriate human uses of the marine environment. In this study, we demonstrate that deep-sea bottom longline fishing has little impact on vulnerable marine ecosystems, reducing bycatch of cold-water corals and limiting additional damage to benthic communities. We found that slow-growing vulnerable species are still common in areas subject to more than 20 years of longlining activity and estimate that one deep-sea bottom trawl will have a similar impact to 296–1,719 longlines, depending on the morphological complexity of the impacted species. Given the pronounced differences in the magnitude of disturbances coupled with its selectivity and low fuel consumption, we suggest that regulated deep-sea longlining can be an alternative to deep-sea bottom trawling.

GROWTH AND MORTALITY OF COMMON OCTOPUS (OCTOPUS VULGARIS) FED A MONOSPECIFIC FISH DIET

ABSTRACT The profitability of octopus ongrowing remains limited because low cost artificial diets have not yet been effectively developed. Therefore, alternative, low cost diets are worth exploring. In this study, we have investigated the growth and mortality of octopuses fed strictly on mackerel (Scomber colias), a low cost fish, readily available in the Azores Archipelago. Different weight classes (150–300; 300–600; and 600–1,000 g) were maintained at two stocking densities; 5 versus 12 individuals (ranging between 0.38–2.72 kg m-3). The trial lasted 72 days and was performed in an open system composed of large rectangular tanks. Each individual was tagged, and growth was followed weekly. Mean instantaneous growth rate (G) varied between 0.67 and 1.47 (% increase in body weight day-1), depending on initial body size. Survival was 100% for octopuses held in tanks at low density. On the other hand, increased aggressive interactions in high density tanks resulted in higher mortality rates (MR), especially for the smallest size class (MR = 66.7%). The results of this study suggest that with a monodiet of mackerel, subadult octopuses of 300 g can reach commercial size (750 g) in 2.5 mo. However, high mortality under elevated stocking densities will hinder commercial profitability with such diet. A proposed approach to increase survival would be to periodically supplement the monodiet with crustacean flesh.

Plastic ingestion in oceanic-stage loggerhead sea turtles (Caretta caretta) off the North Atlantic subtropical gyre

Juvenile oceanic-stage sea turtles are particularly vulnerable to the increasing quantity of plastic coming into the oceans. In this study, we analysed the gastrointestinal tracts of 24 juvenile oceanic-stage loggerheads (Caretta caretta) collected off the North Atlantic subtropical gyre, in the Azores region, a key feeding ground for juvenile loggerheads. Twenty individuals were found to have ingested marine debris (83%), composed exclusively of plastic items (primarily polyethylene and polypropylene) identified by μ-Fourier Transform Infrared Spectroscopy. Large microplastics (1-5mm) represented 25% of the total number of debris and were found in 58% of the individuals sampled. Average number of items was 15.83±6.09 (±SE) per individual, corresponding to a mean dry mass of 1.07±0.41g. The results of this study demonstrate that plastic pollution acts as another stressor for this critical life stage of loggerhead turtles in the North Atlantic.

Marine litter on the seafloor of the Faial-Pico Passage, Azores Archipelago

Plastic pollution in the marine environment attracts much attention from both researchers and the general public. Plastic items and other debris are commonly observed everywhere in the ocean, from the surface down to the deep ocean floor. In this study, we analysed 45.2km of video footage, collected during 56 transects surveying the seafloor of the Faial-Pico Passage in order to quantify the abundance of marine litter and its interactions with benthic fauna. The footage was collected by a Remotely Operated Vehicle (ROV) and a manned submersible at depths ranging between 40 and 525m. The mean litter density in the passage was 0.26±0.03 items·100m-1 (±SE) and was significantly higher between 151 and 250m compared to other depth strata. Overall, derelict fishing gear, mostly made of plastic, were the most common objects found on the seafloor, representing 64% of all items. Although we observed few evidence of direct deleterious effects by the litter, interactions with fauna were observed in more than half of the items. This study makes an important contribution in quantifying the abundance of marine litter on the seafloor of the Azores. The location of the Faial-Pico Passage, close to shore, makes it an appropriate site for long-term monitoring of litter on the seafloor and evaluate the efficiency of upcoming public policies aimed at reducing litter input into the oceans.

Overview of the Ocean Climatology and Its Variability in the Azores Region of the North Atlantic Including Environmental Characteristics at the Seabed

Obtaining a comprehensive knowledge of the spatial and temporal variations of the environmental factors characterising the Azores region is essential for conservation and management purposes. Although many studies are available for the region, there is a need for a general overview of the best available information. Here, we assembled a comprehensive collection of environmental data and briefly described the ocean climatology and its variability in the Azores. Data sources used in this study included remote sensing oceanographic data for 2003-2013 (sea surface temperature, chlorophyll-a concentration, particulate inorganic carbon and particulate organic carbon), derived oceanographic data (primary productivity and North Atlantic oscillation index) for 2003-2013, and in situ data (temperature, salinity, oxygen, phosphate, nitrate and silicate) obtained from the World Ocean Atlas 2013. We have produced 78 geographic datasets of environmental data for the Azores region that were deposited at the World Data Center Pangaea and also made available at the SIGMAR Azores website. As with previous studies, our results confirmed a high spatial, seasonal and inter-annual variability of the marine environment in the Azores region, typical of mid latitudes. For example, lower sea surface temperature was found in the northern part of the study area coinciding with higher values for chlorophyll-a concentration, net primary production, and particulate organic and inorganic carbon. Higher values for some of these parameters were also found on island slopes and some seamounts. Compiled data on the environmental conditions at near-seabed revealed some notable variations across the study area (e.g. oxygen and nutrients) and with depth (e.g. temperature, salinity, and oxygen). Knowledge of these patterns will help improve our understanding of the distribution of many deep-sea organisms such as fish, cold-water corals and sponges, thereby supporting the implementation of marine spatial planning and other management measures. It should be noted, that the assembled datasets suffer from a number of limitations related to the accuracy of remote sensing and global bathymetry data, or to the limited and unevenly distributed historical environmental observations. Accordingly, an effective global network of observing systems for detecting oceanic change with adequate accuracy and precision is still required.

The role of Malcolm Clarke (1930–2013) in the Azores as a scientist and educationist

Malcolm Roy Clarke (1930–2013) was a British teuthologist who made an important contribution to marine science in the Azores archipelago (Portugal). Malcolm started doing research in the Azores from 1980s onward, settling for residency in 2000 after retirement (in 1987). He kept publishing on Azorean cephalopods collaborating in 20% of the peer reviewed works focus- ing on two main areas: dietary studies; and the ecology of cephalopods on seamounts. Since his first visit in 1981, he was involved in the description of the dietary ecology of several cetaceans, seabirds, and large pelagic and deep-water fish. Using his own data, Malcolm revised the association of cephalopods with seamounts, updating and enlarging the different cephalopod groups according to species behaviour and ecology. Malcolm taught several students working in the Azores on cephalopods and beak identification, lecturing the Third International Workshop in Faial (2007). He empowered the recently established research community, by providing important contacts with foreign institutes and informal advice. He collaborated in the regional cetacean stranding network (RACA) and was an active member of the advisory board of the journal Arquipelago—Life and Marine Sciences . But the scientific role of Malcolm Clarke in the Azores went beyond his academic activities. In the last 10 years Malcolm and Dot Clarke dedicated themselves to building and running a museum on Pico Island, showing the biology of the sperm whale and its interaction with squid; a cultural and touristic legacy for future gen- erations to enjoy.

Spatio-temporal variability of beached macro-litter on remote islands of the North Atlantic

Marine litter has been identified as one of the major environmental problems that oceans are currently facing. Worldwide efforts are being made to reduce the input of litter into the oceans, and projects aimed at monitoring their quantities are key to evaluate their success. This study, provide baseline information on the quantities of marine litter found on 42 beaches spread throughout the nine islands of the Azores archipelago, North Atlantic Ocean. A total of 31,439 items were collected throughout the archipelago with an average density of 0.62 ± 0.15 macro-litter items m-2. Of this litter 87% were plastic and its majority (67%) plastic fragments. Six beaches were further monitored every three months for two years. Substrate type and wind exposure were important factors for explaining patterns of litter deposition. Our results highlight that marine litter have the tendency to accumulate in remote islands of the North Atlantic Ocean.

Potency of Barnacle in Aquaculture Industry

Barnacles belong to the Cirripedia group (cirri: cirri, pedia: feet) and are, for the most part, sessile crustaceans that live permanently adhered to a substrate that can be inorganic (rock), organic (coral, molluscs, turtles, whales) and even artificial (plastic, wood) (Southward, 1987). They mainly inhabit marine environments; although some species can resist low salinities in estuarine zones (Arenas, 1971), and are distributed bathymetrically from the high intertidal zone to depths of over 1,000 m (Anderson, 1994). They are gregarious, forming dense “patches” of individuals that can completely cover substrates.

Distribution and composition of floating macro litter off the Azores archipelago and Madeira (NE Atlantic) using opportunistic surveys

The distribution and composition of macro litter floating around oceanic islands is poorly known, especially in the North Atlantic. Due to its isolated location at the fringe of the North Atlantic subtropical gyre, the Azores archipelago has recently been proposed as a potential retention zone for floating litter. To further investigate this assumption, opportunistic surveys from pole-and-line tuna fishing boats were performed from 2015 to 2017 to document (1) the distribution and (2) the composition of the floating macro litter present off the Azores and Madeira islands. Among the 2406 visual transects, 482 floating debris were recorded and were mainly composed of general plastic user items (48%), plastic packaging (21%) and derelict fishing gears (18%). Average number of debris per transect was 0.19 ± 0.5, with a total number ranging between 0 and 5 items per transect. For the majority of transects (84%), no debris was observed, 13% of the transects contained a single item, and only 3% contained more than one item. Although debris between 2.5 and 5 cm were recorded, 93% of the debris were larger than 5 cm. The GLMs showed strong effect of the observer (p < 0.001) and the standardized densities accounting for the observer bias were higher (1.39 ± 0.14 items.km-2) than the observed densities (0.78 ± 0.07 items.km-2). Debris densities were however relatively low and tended to aggregate around the Central group of the Azores (standardized mean: 0.90 ± 0.20 items.km-2). Our findings therefore suggest that most of the debris might originate from far away land-based sources and from fishing activities. This study highlights the potential of fisheries observer programs to obtain cost-effective information on floating macro debris that are essential to support the implementation of the European Marine Strategy Framework Directive.